Formatter changes order of comments.

[randolf-scholz]

class Foo:
    # comment 1
    @abstractmethod
    def foo(self) -> None: ...
    @abstractmethod
    def bar(self) -> None: ...
    # comment 2

    # comment 3
    def baz(self) -> None:
        return None
    # comment 4

becomes

class Foo:
    # comment 1
    @abstractmethod
    def foo(self) -> None: ...
    @abstractmethod
    def bar(self) -> None: ...

    # comment 3
    # comment 2
    def baz(self) -> None:
        return None

    # comment 4

[ruff-playground]

1. Comments 2 and 3 get swapped.
2. An extra space is inserted after def bar. Since these are stubs, no space should be inserted. (for instance, comment 1/2 can be # region/#endregion). But this is just my opinion.

[randolf-scholz]

Another example, where the comment actually moves inside another function def.

class Foo:
    @abstractmethod
    def foo(self) -> None: ...
    # comment 1

    def baz(self) -> None:
        return None

becomes

class Foo:
    @abstractmethod
    def foo(self) -> None: ...

    def baz(self) -> None:
    # comment 1
        return None

https://play.ruff.rs/973d0af8-e586-4fc0-9aec-28fecf0dc047

[MichaReiser]

You're good at finding comment reordering bugs and thank you so much at taking the time to report them!

Uhh, the second one is really bad. Let me have a look.

What's interesting is that all comments are associated with the right method. So this is a rendering bug and not a placement bug (logic where we figure out where a comment is most likely to belong).

https://play.ruff.rs/5e5ae359-b017-4d82-ac47-2c77f254f161

[MichaReiser]

To make it worse, this is not even related to classes nor does it require decorators. https://play.ruff.rs/2bcde006-72e6-409f-9fa9-659ef78d7944

[randolf-scholz]

I would suspect this is somehow related to special logic for formatting stub implementations #8357

[MichaReiser]

Yeah, that's a great observation. The issue is that, for stubs, we don't write extra empty lines between the comment and the next function, which drips over the formatting.

[MichaReiser]

@randolf-scholz thanks for debugging this together. The fix turned out to be not that bad :)